Recurrent coliform mastitis in the dairy cow.

Daily monitoring of milk over a 120-day period for bacteria and neutrophil counts revealed that following experimental E coli mastitis, five out of 28 infections resulted in the development of a long continued and recurring condition. Intermittent periods of acute inflammation were observed in the gland, pyrexia was noted, and if bacteria were isolated they were always of the same serotype as the original infecting strain. Failure to isolate bacteria and the lack of overt inflammation during periods of remission suggested that the bacteria were not in the gland cistern but within gland tissue. In one animal antibiotic therapy with a drug which was active in vitro was ineffective in vivo. However another antibiotic proved effective.